Fail Safe Cooling

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: If the driver is using a high percentage of throttle travel (for example, an overtaking maneuver) when the PCM starts, engine deactivation will be delayed for 10 seconds.

NOTE: After the cylinder deactivation operation has begun, the engine will not revert to operating on all cylinders, even if the temperature should fall, until the ignition is switched OFF and then ON again.

NOTE: The Malfunction Indicator Lamp (MIL) can only be extinguished by using a scan tool after the fault has been rectified and the DTC cleared.

The vehicle has a strategy built into the PCM that will control the engine if it starts to overheat.

Stage 1 of the strategy will commence if the engine starts to overheat. The Cylinder Head Temperature (CHT) sensor transmits a signal to the PCM, which then moves the temperature gauge pointer into the red zone.

If the engine is not switched OFF and the temperature continues to rise, the powertrain check lamp is illuminated. This indicates to the driver that the engine is approaching critical limits and should be stopped. At this point, DTC P1285 is set in the PCM and can be retrieved using a scan tool.

Stage 2 of the strategy will commence if the lamp and temperature gauge are ignored by the driver. The PCM will start to control the engine by cutting out cylinders and restricting the rpm to below 3,000 rpm. Simultaneously, the MIL will be illuminated. This indicates that long-term engine damage can occur and vehicle emissions will be affected. At this point, DTC 1299 is set in the PCM and can be retrieved using a scan tool.

Air is then drawn into the deactivated cylinders. This helps to control the temperature of the engine internal components. The deactivated cylinders are alternated to allow even cooling of all the cylinders.

Stage 3 of the strategy will commence if the engine temperature still continues to rise. This will result in the engine being totally disabled before major engine damage or seizure occurs. The powertrain check lamp will begin to flash, indicating to the driver that the engine will be switched OFF after 30 seconds. This allows the driver time to choose a suitable parking place.